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OUR <br /> acceptors, (d) evaluation of competitive inhibitors, and (e) evaluation of cis-l,2-dichloroethene <br /> (cis-1,2-DCE) stall; and (4) conduct an assessment and cost benefit analysis of different substrates. <br /> Given the nature of the natural transformation of the Hazardous Substances within the deeper <br /> B-zone aquifer, LFR recommended monitoring this zone instead of implementing active ERD. <br /> However, in its letter dated May 11, 2007, the RWQCB recommended implementing ERD in both <br /> the A and B zones due to a lack of evidence that Hazardous Substances are degrading completely to <br /> harmless end products. As instructed by the Lincoln Center Environmental Remediation Trust, in <br /> May 2007, LFR collected groundwater samples from three B-zone and one A-zone monitoring <br /> wells. These samples were analyzed for a full suite of chemical parameters pertinent to ERD and <br /> monitored natural attenuation (MNA) remedies. The results of this voluntary sampling event are <br /> presented in the Phase V IRA Detailed Plan. Results show that contaminants in the B zone are <br /> degrading to harmless end products, and that, relative to the A zone, geochemical conditions in the <br /> B zone are favorable to natural reductive dechlorination. These results are documented in the Phase <br /> V IRA Detailed Plan. Given these findings, the Phase V IRA Detailed Plan proposes to monitor the <br /> B zone for MNA parameters and includes provisions for implementing active ERD in this zone if <br /> the monitoring data show that favorable reductive conditions are not persistent. <br /> If you have any questions or require additional information, please call Don Bradshaw at (512) <br /> 8954003 or Lucas Goldstein at (510) 652-4500. <br /> Sincerely, <br /> cs <br /> Donald T. Bradshaw, P.G. Lucas Goldstein, P.G., E.I.T. <br /> Principal Hydrogeologist Senior Engineer <br /> Enclosure <br /> cc: Marie T. McCrink, Regional Water Quality Control Board <br /> John Farr, Ph.D., P.E., Farr Associates <br /> David Gouker, City of Stockton Public Library, Margaret Klausner Troke Branch <br /> David Sadoff, AIG Environmental <br /> David B. Durrett, Cohen&Durrett <br /> Phil Johnson, Sims Grupe Management <br /> Joe Salazar Jr., Lewis Brisbois Bisgaard& Smith LLP <br /> Katherine Wagner, Downey, Brand, Seymour&Rohwer <br /> .p-phV IRA-Sep07-Final-06750.dm:1(r 2 <br />